Motor graders having a mold board or blade for scraping a surface are commonly known and extensively used in highway and airport construction and maintenance. In many road construction projects, the grader blade is passed over a surface with the mold board smoothing and scraping off irregularities to provide a finished surface which may then be either paved or coated with oil or asphaltic material to provide a smooth hard surface. A separate piece of equipment requiring its own operator and having a rotary boom mounted thereon is then passed over the finished surface to clear away the finer debris left behind once the construction is completed. In other situations, shoulder repair work may be required on existing paved surfaces. In these situations, a motor grader blade is used to provide a reworked shoulder surface. This procedure may also require other earth moving equipment in the area, creating a need for general clean up of the road surface with a rotary boom for safety reasons as well as appearance. Thus, specialized pieces of equipment and skilled operators are needed in most instances, which contribute significantly to the overall cost. Most road and highway maintenance organizations do in fact need both a grader and a broom.
At present, there is no single apparatus which satisfactorily combines the functions of the motor grader and the rotary broom in such a way that the mold board or the broom can be used separately or together as desired, without time consuming and complicated broom removal or mounting procedures. The need exists, therefor, for a combined grader and broom in which the mold board and the broom may be independently vertically adjustable so that each may be used alternately or together without interference from the other. Preferably, such a device should not be significantly more complicated to operate than a grader alone or a broom alone, and would include automatic side shifting of the broom independently or concurrently with the blade, as well as vertical adjustment of the broom, to avoid its interference with the structure of the motor grader in any position of operation. A prescribed constant downward pressure exerted by the broom, as well as its speed and direction of rotation, should also be automatically controlled.